Prospective validation of gallium-68 ( 68Ga) prostate specific membrane antigen (PSMA)-PET/CT in initial staging of prostate cancer is lacking. This study evaluates diagnostic accuracy of 68Ga-PSMA-PET/CT in detection of lymph node metastases in patients with intermediate-high risk prostate cancer.
Materials and Methods
From October 2017 to October 2018, newly diagnosed prostate cancer patients with negative bone scan and >10% MSKCC risk of lymph node metastases were prospectively included. In candidates for extended pelvic lymph node dissection, 68Ga-PSMA-PET/CT prior to planned surgery was performed. Scan results were evaluated in a second tumor board meeting to assess potential change of management. Sensitivity, specificity, positive and negative predictive value for the detection of lymph node metastases were calculated per patient and per resection template using histopathology as a reference. PET-based change of management was also reported.
A total of 103 patients were eligible for analysis. Ninety-seven extended pelvic lymph node dissections were performed. Forty-one patients (42.3%) had 85 lymph node metastases. Seventeen patients were PET-positive, resulting in a patient-based sensitivity of 41.5% (95% CI: 26.7%-57.8%) for the detection of lymph node metastases. Patient-based specificity was 90.9% (95% CI: 79.3%-96.6%), positive predictive value was 77.3% (95% CI: 54.2%-91.3%) and negative predictive value was 67.6% (95% CI: 55.6%-77.7%). PET-based change of management was observed in 13 patients (12.6%).
In newly diagnosed prostate cancer patients with >10% MSKCC risk of lymph node involvement, 68Ga-PSMA-PET/CT detects lymph node metastases with high specificity and moderate sensitivity; this leads to change of management in 12.6% of patients.